Piston-packing



L. 0. MARSHALL.

PISTON PACKING.

APPLICATION FILED OCT. 27, I919.

1 ,400,560, Patented Dec 20, 1921.

Z I: II

II lmw II UNITED STATES PATENT OFFICE.

LEWIS G. MARSHALL, OF WALPOLE, MASSACHUSETTS, ASSIGNOR TO PRESSURE PROOF PISTON RING COMPANY, OF BOSTON, MASSACHUSETTS, A. CORPORATION OF MASSA- CHUSETTS.

PISTON-PACKING.

Specification of Letters Patent.

Patented Dec. 20, 1921.

To all whom it may concern:

Be it known that I, Lewis G. MARSHALL, a citizen of the United States, and resident of Walpole, in the county of Norfolk and State of Massachusetts have invented new and useful Improvements in Piston-Packing, of which the following is a specification.

This invention relates to piston packings and while adapted to the packing of pistons generally, it is especially designed for the packing of pistons of internal combustion engines. In such engines in operation the cylinder is cooled while the piston is hot and the latter therefore expands more than the cylinder and must fit loosely within the cylinder to avoid binding. In order to main- I tain the high compression which is necessary, the piston is provided with packing rings which not only must fit tightly against the cylinder wall, but must make a tight joint with the grooves of the piston within which they are positioned, to prevent leakage underneath the piston rings.

The principal object of the present invention is to provide a novel and improved metallic piston packing which shall accomplish these results and which shall also be simple in construction and free from multiplicity of parts and complexity of construction.

The invention will now be described in connection with certain specific embodiments of the genus of t e invention.

In the accomp nying drawings- Figure 1 is a partial side elevation of a piston head showing a packing positioned in a roove therein;

ig. '2 is a partial side elevation of a piston head showing a packing in cross section positioned within a groove therein;

Fig. 3 is an enlarged detail view in cross section, illustrating the form of packing shown in'Figs. 1 and 2;

Figs. 4 to 7 inclusive are enlarged detail views in cross section, illustrating modified forms of packings;

Fig. 8 is a,perspective view of a spring steel forcing or follower ring which may be employed with the packings illustrated in Fi s. 1to7;and

ig.'9 is an enlarged detail view in cross section, illustrating a still further modification of the invention.

Referring to Figs. 1, 2 and 3 of the drawings, l represents a packing ring divided at a single point 2, but otherwise continuous, and preferably made of gray cast iron or other suitable material; This ring is substantially trapeziform in cross-section as shown in Fig. 3, having its peripheral face 3 disposed at right angles to its faces 4 and 5, and having an external diameter preferably aboutequal to the diameter of the cylinder bore. The inner face 6 of the ring 1 is beveled with respect to the peripheral face 3 at an angle, for example, of about 25. The edge of the ring at the juncture of the beveledface 6 and the face 5 is cut away to form a rentrant shoulder 7 for a purpose hereinafter described. A second ring 8 of cast iron or other suitable material is provided having a trapeziform cross-sectlon, the outer face 9 of which is beveled at the same angle as the beveled face 6 of the ring 1 and 1s adapted to contact with the face 6. The ring 8 is divided at only one point to enable its insertion in the groove of the cylinder and is preferably a spring ring so formed as to exert a slight pressure against the inner face of ring 1. The position of the rings land 8 when assembled is best shown in Figs. 2 and 3. The spring ring 10 is a forcing or follower ring preferably of spring steel, divided ata single point and as shown in Fig. 8 is crinkled or sinuous in a directipn perpendicular to the plane of its generation, the sinuous form of the ring enabling it to expand both radially and in a direction perpendicular thereto.

The ring 10 rests upon the radial wall 11 of the groove 12 in the piston head 13 and engages beneath the ring 8 and against the shoulder 7 of the ring 1 under compression thereby forcing the ring 8 against the radial wall 14 of'the groove to insure a tight joint between the ring and the wall 14: of the groove 12 and forcing the ring 1 radially against the cylinder wall.

The three rings are assembled in the circumferential groove 12 of the piston head 13 insuch positions that the lines of division of the rings break joint.

so that the clefts are in broken joint relation to each other whereby the packing ring 1 is.

forced outwardly with more nearly even pressure throughout its periphery and the tendency of the ring to expand into an elliptical form thereby wearing the bore of the cylinder unevenly, is diminished. When assembled in the groove of the piston-head as shown in Figs. 1, 2 and 3, the ring 1 fits the cylinder bore and is urged into contact therewith by the sprin ring 8 and also by the follower ring 10,. The rin 10 ur es the ring 8 upwardly against the wa l 14 the groove and the ring 8 due to its expansion and to its beveled contact with the inner face of the ring lurges the ring 1 both in a radial direc .tion against thev cylinder wall and in a 11 of the groove; The'foll'ower ring downward direction against the radial wall cause of its expansion radially agalnst the an ring 16 dueto' its expansion and to its-- shoul'der 7 of the ring 1 urges the lower por tion of thering 1 radially against the cylinder wall and tends to offset any tendency of the ring'l to twist due to the pressure of the ring 8 against its upper region. The contact between ring 8 and the wall 1.4 of the groove, the contact between ring -1 and the wall 11 of the groove and the contact between the ring 1 and the cylinder wall insure a gas tight 'oint betweenthepiston head and the cylin er wall.

The modified form of packing shown in Fig. 4 is substantially similar to the packing shown' 'in Figs; 1', 2 and-3, excepting that the slope of the beveledsurface of engage" ment between the packing ring '15 and the follower ring 16 is reversed'. The action of thespring ring 10 upon the ring 16 urges the rin 16 "against the wall 14 of the groove,

beveled contactwith the inner face of the J ring 15 urges the ringl5 radially against the cylinder wall and toward'the wall 14 of the groove. Both rings thus unite in effecting a seal with the wall 14 of the groove.

sprin ring 10 mightdf desired be so posi tlone against the shoulder 17 of the ring 15 as to exert an upward pressure against the ring 15to urge it toward the wall-'14 of the groove; as well as to urge ring 16 toward the wall 14. 1

In Fi 5 a further modified form of packing is i ustrated. Both the packing ring 18 and the spring follower ring 19 are substantially rectangular in cross-section, the inner peripheral face of the ring 18 against which the ring 19 contacts being concentric'with the outer peripheral face of the packing ring 18. The ring 18 is provided with a shoulder 20 as in the previously described embodiments, and the spring ring 10 is positioned beneath the ring 19 and against the shoulder 20 so as to urge both rings 18 and 19 against; lthe;wall 14 o -the beveled'contact between the rin The T ollower ring 19. and

tend into contact with the upper wall 14 of the groove. Ring 22 upon expanding urges er the packing ring 21 against the cylin the omission of the shoulder'from the packing ring 23. The packing functions in the same'manner as the packing of Fig. 4.

Instead of employing an annular steel follower ring 10 of the type disclosed in Fig. 8, a plurality of coiled springs 24 may be positioned as shown in Fig. 9 between the lower wall 11 of the groove and the lower face of the spring'follower ring 25 for forcing the rin 25 upwardly against the radial wall 14 of t e roove. These springs may be spaced at suitable intervals around the groove and held in position by extending into suitable holes in the ring 25 as shown at 26. This packing functions in the same general manner as the packing shown in Fig. 3, 25 and the packing ring 27 urging the packing ring 27 both radially against the cylinder wall and downwardly against the lowerradial wall '11 of the groove.

In certain of the figures the follower ring .10 has been shown as formed from wire ground or drawn fiat on one side, and in other figures as formed from wire ground or drawn flat on diametrically opposite'sides. It is of course obvious that a wire follower ring of either form or of any other suitable cross-section might be used interchan eably with any one. of the disclosed embodiments of the invention. The packings disclosed might alsobe reversed in the grooves of the piston head'the' follower ring 10 being posi- 'tioned between the upper radial wall 14 of the groove and the spring and packing rings.

' I claim: I

1. In combination with an integrally formed piston having a peripheral groove provided with radial walls, a packing within said groove comprising a packing ring, ares'ilient rin'giengaging the inner eripheral surface of said packmg ring, an yieldin means disposed between said second ring an a radial wall of said groove, said means being c'oiistructed and arranged to urge said resilient ring into engagement with the opposite radial wall.

2. In combination with an integrallyformed piston having a. peripheral groove therein, a packing ring in sai groove, a resilient ring engagin the inner peripheral surface of sai pac 'ng ring, and 5 ring means constructed and arranged sim taneously to urge said resilient ring in an axial direction and to expand said packing ring radially.

' 3. In combination with an integrally formed piston having a peripheral groove provided with'radial walls, a packing. in said groove comprising apackingring, a spring ring engaging the, innerperipheral surface of said packing ring, and spring means disposed between said spring ring and a radial wall of said groove.

p 4. In combination with a piston'having an annular groove, a packing in said groove comprising a packing ring,x'a second ring engaging the inner peripheral surface of said packing ring, and a spring, follower ring disposed between said second ring and a radial wall of said groove and having engagement with said packing ring.

5. In combination with a piston having an annular groove therein, a packing in said groove comprising a packing ring,.a resilient ring engaging the inner peripheral surface of said packing ring, and a spring'follower ring disposed between said second ring and a radial wall of said groove, such spring fol lower ring directly engaging a portion of the inner peripheral surface of the packing ring.

annular groove, a packing in said groove comprising a packing ring, a spring ring en- In combination with a piston having an shoulder on its inner peripheral surface, a spring ring engaging the inner peripheral surface of said packing ring, and a sinuous spring fo'llower ring disposed between said spring ring and a radial wall of said groove and in contact with the shouldered portion of said packing ring.

8. In combination with a piston having an annular groove, a packing in said groove comprising a packing ring having a beveled inner' face, an annular shoulder formed in said beveled face, a second spring ring with;

in said groove and having an outer beveled face corresponding tothe beveled face of the 'acking ring, and a sinuous spring follower ring disposed between said second ring anda radial wall of'said groove and in contact with the shouldered portion of said packing ring whereby said spring ring urges with the shouldered portion of said packing ring whereby said follower ring urges sai spring ring and said packing ring against a radial Wall 'of the groove and urges said packing ring radially toward the wall of the cylinder. j Signed by me at Boston, Massachusetts,

this 21st day of October, 1919.

" LEWIS C. MARSHALL. 

